1. Field of the Invention
The present invention relates to an engine air supply control method, intended for example for the control of a turbocharged engine and more particularly for an engine of this kind intended for a private automobile.
2. Description of the Related Art
Generally, the air supply in an engine is controlled by measuring the mass air flow through the engine. There are many methods of determining this mass flow. For example, there is a known way of measuring the speed and temperature of the air in a known section of the air supply system, for example at the throttle valve controlling the air flow into the engine. Such a measurement is carried out, for example, in racing vehicles and motorcycles. Another method of determining this flow consists in measuring the pressure in the intake manifold, the engine speed and the air temperature. This method is used in motor vehicles at the present time. For top-range vehicles, this flow is sometimes also measured by means of a wire which is heated and through which an electric current is passed, the resistance of the wire being measured by means of a Wheatstone bridge. All these measurement methods are known to those skilled in the art and are not detailed here.
In a turbocharged engine, and particularly in such an engine fitted with an electric throttle valve, the importance of measuring the exhaust pressure for the determination of the loss of torque is apparent, more particularly in relatively low-capacity engines. This is because a request from the driver via the accelerator pedal can be interpreted as the request for a given torque. It is then desirable to determine the torque of the engine, and therefore also the losses of torque within the engine due, for example, to friction and back pressure, in order to be able to respond to this request. The exhaust pressure is then a factor to be taken into account for the determination of the losses of torque within the engine.